A program developed to study the developmental regulation of cell motility and chemotaxis in three systems: Dictyostelium discoideum, chick myoblasts, and the growth cone of identified neuros in Helisoma. A core facility will be employed to study cell behaviors under a variety of chemotactic annd stimulatory conditions. In the study of Dictyostelium, 1) a complete description will be developed of chemotactic and chemokinetic responsiveness of single amebae and groups of amebae to cAMP and folic acid during growth, morphogenesis and dedifferentiation; 2) chemotactic variants will be isolated; and 3) studies of cytoskeletal and membrane changes accompanying chemotactic changes will be initiated. In the study of myoblasts, 1) confirmation and characterization of chemotactic responsiveness to platelet-derived growth factor, horse serum, and chick embryo extract will be performed; 2) polyclonal antibodies to the attractants will be generated and tested for effects on chemotaxis; and 3) the vasculature will be tested as a source of attractant. In the study of growth cones, 1) movement of growth cones in relation to a variety of extrinsic cues will be analysed; 2) conditioned perfusates will be tested on growth cone behavior; and 3) two microelectrode voltage clamp ad patch-clamp will be applied to study ion channels. Besides use of a common core facility, this program project is developed around experiments common to the three systems and a number of collaborative efforts dependent upon the diverse expertise of the three principal investigators.